This invention deals with a method of quality control testing and leak detection for roofing seams. The method is non-destructive and can be applied to already existing old roof seams, newly installed roof seams, or seams in factory manufactured roofing materials before they are installed in a roofing system.
Large industrial and commercial buildings quite typically have flat or near flat roof surfaces. These roof surfaces generally are multi-layered, that is, they generally have in combination a roof supporting structure which is surmounted by a deck, and various layers of water impermeable membranes, thermal insulation and a ballast layer to assist in holding the entire roof from being blown away.
Single ply roof membranes of elastomeric or thermoplastic materials are seamed by bonding the roof materials together using sheets of varying widths and lengths to form an integrated membrane for covering the roof surface. The quality and integrity of the membrane is dependent on the quality of the seams and one of the largest problems in producing such large flat roofs is the quality of the bonds in the seams that are provided in the single ply membranes that are used as the water impermeable layers in such roofs. This problem is of continual concern to the industry because the leakage problem is so severe. It causes degradation of other roof components and such leaks are difficult to locate.
The weatherable and essentially inert materials that are used for the single ply roofing materials are known to have multiple problems with bonding to themselves and to each other, and consequently, the seams created from these materials are an unknown entity. For example, practitioners experience false welds or bonds due to moisture on the surface of the material. Welding guns may be cold when they were thought to be heat sealing. Marks used for stopping and starting the bonding may have been missed and a problem with the use of reinforcement, which boils off and blisters the polymeric materials and ruptures the bonds are all common faults in the application of roofs.
The quality of a seam once it is manufactured cannot be determined in a non-destructive fashion. On visual examination, all seams look good if just the last outside 1/16 inch of the nominally 11/2 inch wide seam is sealed.
The use of mechanical probing has been carried out on the this very thin line of bond at the very extreme edge of the seam, fortunately, it is the easiest part to seam, but even knowing the extent of bonding of this leading edge, does not give the true picture of the area or quality of the bond of the entire seam.
Caulk is sometimes used for protecting such seams and in a number of cases becomes the only bonded and sealed portion of such seams but is not considered to be a very effective solution to a fully bonded seam area.
Laboratory testing has included such practices as ultrasound, pulse-echo techniques, infra-red imagery and so forth, but these have not proven adaptable for field use.
The more progressive commercial roofing companies tend to use a T-peel test to check the quality of the seams during construction or when a problem roof demands some attention. This T-peel test is a very simple stress/strain test wherein two sides of a lapped roofing material are put into the vertical holding jigs of a tensile testing machine and pulled at an angle of 180.degree. from each other, and at a specific rate. Such machines are manufactured by the Instron Corporation and are hence sometimes called the "Instron test". The machines are designed such that the loads required to pull the laps apart are directly recorded along with the width of the sample so that the load/area normally reported in units of pound/inch may be observed. Using this type of test, the range of strength for those seams that are bonded together is about 4 to 8 pounds per inch of width, and fused materials, i.e. those that are essentially melted together, range to about 20 to 40 pounds per inch of width. This test has proven to be ineffective and insensitive to improperly prepared surfaces. Obviously, a further difficulty with this type of quality control testing is that it is a destructive test, taking some time, usually in a site away from the construction location. Also, it causes damage to the roof at several places along each seam and makes it very difficult for the contractor to repair certain areas of the roof as very often the roof surface is not clean.
Further, there is an ongoing disagreement among those in the industry as to whether the test truly represents the quality of the seams because only small portions of the seams are being tested in width and length. The small samples tested are supposed to represent the many miles of seams on a roof, but is believed by the more progressive commercial roofers that such is not the case. Measuring the full area of the bonding of seams is a valuable asset in addition to being able to measure the strength of the bond which is a measure of the quality of the seam, and thus, the instant invention is timely.
Since applicant was not able to locate any patents or publications in the prior art regarding the instant invention, it is believed by the applicant that the method is new and novel.